diff --git a/swh/loader/git/loader.py b/swh/loader/git/loader.py
--- a/swh/loader/git/loader.py
+++ b/swh/loader/git/loader.py
@@ -266,7 +266,12 @@
         """Compute the project name from the archive's path.
 
         """
-        return os.path.basename(os.path.dirname(archive_path))
+        archive_name = os.path.basename(archive_path)
+        for ext in ('.zip', '.tar.gz', '.tgz'):
+            if archive_name.lower().endswith(ext):
+                archive_name = archive_name[:-len(ext)]
+                break
+        return archive_name
 
     def prepare_origin_visit(self, origin_url, archive_path, visit_date):
         self._prepare_origin_visit(origin_url, visit_date)
diff --git a/swh/loader/git/tests/test_loader.py b/swh/loader/git/tests/test_loader.py
--- a/swh/loader/git/tests/test_loader.py
+++ b/swh/loader/git/tests/test_loader.py
@@ -4,8 +4,6 @@
 # See top-level LICENSE file for more information
 
 import os.path
-import zipfile
-import tempfile
 import subprocess
 
 from swh.loader.git.loader import GitLoader, GitLoaderFromArchive
@@ -137,32 +135,10 @@
 
     """
     def setUp(self):
-        super().setUp('testrepo.tgz', True)
-        self._setup_zip()
+        super().setUp('testrepo.tgz', False)
         self.loader = GitLoaderFromArchiveTest()
         self.storage = self.loader.storage
 
-    def _setup_zip(self):
-        self._zip_file = tempfile.NamedTemporaryFile('ab', suffix='.zip')
-        dest_dir = os.path.normpath(self.destination_path) + '/'
-        with zipfile.ZipFile(self._zip_file, 'a') as zip_writer:
-            for root, dirs, files in os.walk(dest_dir):
-                assert root.startswith(dest_dir)
-                relative_root = os.path.join(
-                        'testrepo',
-                        root[len(dest_dir):])
-                for file_ in files:
-                    zip_writer.write(
-                            filename=os.path.join(root, file_),
-                            arcname=os.path.join(relative_root, file_))
-        self.destination_path = self._zip_file.name
-        self.tmp_root_path = None
-        self.repo_url = 'file://' + self.destination_path
-
-    def tearDown(self):
-        self._zip_file.close()
-        super().tearDown()
-
     def load(self):
         return self.loader.load(
             origin_url=self.repo_url,
diff --git a/swh/loader/git/utils.py b/swh/loader/git/utils.py
--- a/swh/loader/git/utils.py
+++ b/swh/loader/git/utils.py
@@ -10,7 +10,7 @@
 import shutil
 import tempfile
 
-from subprocess import call
+from swh.core import tarball
 
 
 def init_git_repo_from_archive(project_name, archive_path,
@@ -41,11 +41,18 @@
 
     try:
         # create the repository that will be loaded with the dump
-        r = call(['unzip', '-q', '-o', archive_path, '-d', temp_dir])
-        if r != 0:
-            raise ValueError('Failed to uncompress archive %s' % archive_path)
-
+        tarball.uncompress(archive_path, temp_dir)
         repo_path = os.path.join(temp_dir, project_name)
+        # tarball content may not be as expected (e.g. no top level directory
+        # or a top level directory with a name different from project_name),
+        # so try to make it loadable anyway
+        if not os.path.exists(repo_path):
+            os.mkdir(repo_path)
+            for root, dirs, files in os.walk(temp_dir):
+                if '.git' in dirs:
+                    shutil.copytree(os.path.join(root, '.git'),
+                                    os.path.join(repo_path, '.git'))
+                    break
         return temp_dir, repo_path
     except Exception as e:
         shutil.rmtree(temp_dir)